A Guide to Pruning Trees and Shrubs

Pruning is an essential part of gardening. Essential, but a little intimidating at first because it’s a broad subject. That said, there are some basic rules that apply to most trees and shrubs that will get you started.

There are a number of reasons to prune; the most obvious is for safety, to keep a branch from doing damage or harm by falling or rubbing against something like a building or another tree. Other important reasons include:

• Removing dead, diseased or damaged wood
• Shaping to make a plant bushier, reduce the size and bulk, or slow down growth
• Thinning to increase light penetration and airflow and reduce the possibility of disease
• Rejuvenation to encourage growth, blooming and fruit

Correctly pruning trees and shrubs can help with everything listed above and, most importantly, help maintain the health of your plants. Proper techniques and timing ensure the best results.

The Right Tools

You may need fewer tools to prune than you think!  

Secateurs or hand pruners work well on smaller branches.

Loppers or lopping shears have longer handles for more leverage and are ideal for medium-sized branches.

A pruning saw works best for larger branches.

Electric or manual hedge shears are best for cutting a tidy wall of foliage like hedges and shaped evergreens.

The key with garden tools is to make sure they’re sharp and sterile. This can prevent the spread of disease. Clean tool blades with rubbing alcohol after trimming each branch.

When to Prune

Pruning timing requires some research as it depends on the species of the plant and the result you’re aiming to achieve. For example, some trees may be best pruned in the winter while they’re dormant and buds have not yet appeared. To shape a tree, it’s easier to prune before the leaves have formed so that all of the branches can clearly be seen. Pruning early in the gardening season will invigorate the tree. Conversely, pruning after the tree has formed leaves in June will tend to slow down growth.

When pruning flowering trees and bushes, there are other timing considerations. Some ornamentals bloom on branches that grew the previous year. Pruning those branches too early will result in fewer or no blooms. For these plants, it’s best to wait until after they have bloomed.

If you’re unsure about pruning timing for your tree or shrub, this is a fairly comprehensive list to use as a guide. We have also linked other resources below this article.

In general, late fall or early winter is not the time to prune any plant as it encourages new growth, which may be damaged by colder weather.

Pruning Techniques

While some trees may require specific care (pines, for example), here are the basic techniques for pruning trees and shrubs. It’s a good idea to know these basics before you head out to begin cutting branches.

Examine the branch, buds and shoots before cutting. Cutting above a bud facing away from the trunk of the tree will have the branch continue to grow in that direction.

Cut on a 45° angle just above a bud whenever possible. Keep your cut above the lowest bud (the bud closest to the trunk), or the branch will die back.

Before removing a large branch, cut ⅔ off the end of the length to reduce the weight. Once the bulk of the branch has been removed, then cut the rest of the branch away from the trunk by cutting close to, but not into, the “collar” of the branch where it meets the trunk of the tree.

Now You’re Ready to Begin Cutting!

Now that you know the techniques for pruning, where do you begin? Here’s a logical set of steps to follow:

1 - Remove any dead or diseased wood

2 - Remove any branches that are crossing and rubbing together. For a shrub that’s too crowded, remove the thickest branches down to the ground first  

3 - Remove water sprouts

4 - Stand back and observe the shape of the tree. If anything is not pleasing about the look (lopsided growth or branches growing too close together or at a sharp angle to the trunk, for example), begin removing or trimming back one unsightly branch at a time. Observing the shape between each cut

5 - Remove any suckers or stubs

Follow The ⅓ Rule!

Once you start, pruning can be fun, but be careful not to get too carried away. Trim up to ⅓ off of an established plant (not a newly transplanted tree or shrub) in one growing season - maximum. Cutting off too much can stress the plant and impact its overall health.

Lastly, know that you can always hire a certified arborist if the task is too much or the tree is simply too large!

Other Resources:

• City of Moose Jaw: Pruning Trees 
• Landscape Ontario: Pruning Shrubs and Evergreens
• Ontario Government: Pruning Fruit Trees
• University of Georgia: Pruning Ornamental Plants